Dyeable dextrin-modified latex treated article



United States Patent US. Cl. 818 7 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a rubber coated textile fabric comprising a textile fabric substrate and an elastomeric polymer film coating thereon wherein the polymer film contains a dextrin dye acceptor which renders the clastomeric polymer film dyeable with the identical textile dyes which are capable of dyeing the textile fabric substrate.

This invention relates to a dyeable latex compound which is usually applied to the back of textile articles and in particular relates to the addition of dextrin, to a latex of an elastomeric polymer which latex is usually applied to the back of a textile fabric substrate and cured, wherein the dextrin renders the cured latex film dyeable with the identical textile dyestuffs used to dye the textile fabric substrate.

In accordancewith the present invention, a layer of compounded latex which contains dextrin is applied by any suitable means to a dyeable substrate such as the back of a textile fabric, and said layer is dried and cured to a film whereupon both the textile fabric and substrate and latex film are dyed simultaneously in one dye bath. A latex is a dispersion of synthetic rubber or natural rubber in an aqueous medium. The terms compounding a latex. or compounded latex used in this specification describe the selection of additives and their incorporation into the latex of the synthetic or natural rubber so as to give a homogeneous mixture ready for subsequent processing steps. In accordance with the present invention, the latex film and the textile fabric substrate both absorb ordinary textile dyes from the dye solution. The dye is absorbed and fixed by both physical and chemical attraction into the textile fabric substrate and the cured latex film due to the dextrin, and as a result, the dyes in the textile fabric substrate and cured latex film are fast to washing (leaching), light, and crocking. Thus the present invention provides a novel method so that both a textile fabric substrate and a cured latex film which has been applied thereon are dyed simultaneously in the same dye bath to the same color intensity.

Latex coatings are applied to numerous textile fabrics in order to (1) increase the weight of the goods, (2) to prevent seam slippage, (3) to improve the hand and (4) to reduce edge tear. It has been the experience in the prior art that when latex or latex compounds, usually white to off-white in color, are applied to dyed pieces of fabric, the latex film can be detected when viewing the fabrics face, that is, when viewing the fabric from the non-coated side. This detection of the latex through the substrate is called the grinning effect because the white color of the latex compound shows a sharp contrast with the colored face of the fabric. One method which has been used commercially to reduce the grinning effect is 3,508,854 Patented Apr. 28, 1970 the use of a pigmentation process. In a pigmentation process, the latex is colored with pigment so that the color of the latex will approximate or correspond to the face shade of the textile fabric substrate which is to be dyed after the latex is applied thereon. The latex compound is applied to the back of the textile fabric substrate and is dried and cured. The textile fabric containing the pigmented latex film is dyed. The color of the pigmented latex corresponds to the textile fabric so that relatively no grinning effect from the pigmented latex film occurs. This process has a number of undesirable features. Among them are: (1) An individual latex compound must be pigmented to the color to which the fabric will eventually be dyed. (2) An excess of latex compound which has been pigmented to match a particular face shade is often wasted since it cannot be used on fabrics that will be dyed eventually a different color. (3) The pigmentation of the latex does not eliminate the dyeing process since the textile still has to be dyed to a specific color. (4) Woven fabrics that contain more than one class of fibers may be cross-dyed (e.g., in a given fabric one class of fibers may be dyed one color and another class of fibers may be dyed a different color), and since the latex which is pigmented to only one shade or color is applied to a fabric, an undesirable contrast is often present in many cases due to the latex showing through the face of the light colored cross-dyed fabric.

Elastomeric latices are extremelydifiicult, if not impossible to dye with most conventional textile dyes since they lackdye receptive site's. It was because of this: lack of dyeability that the above noted pigmentation process was developed-We have performed extensive tests to determine whether latices of elastomeric polymers can be modified to become dyeable by the addition of dye acceptor compounds to said latices, and if so, exactly which dye acceptor compounds work effectively when incorporated into the various latices. The results of these tests have shown that when certain cellulosic or cellulosic derivative compounds such as hydroxy-ethyl or hydroxymethyl cellulose or well-known dye acceptor compounds such as polyvinylpyrrolidone are added to latex and an attempt is made to dye the latex with conventional textile dyes, a number of adverse effects result such as: (1) leaching out of the dye acceptor into the dye bath, (2) thickening or coagulation of the latex compound before or during application unless an excess of stabilizer is used (stabilizers detract from the coating characteristics of the latex), (3) certain dyes are preferentially absorbed and other dyes are not absorbed at all. Certain cationic type starches can be added to a latex without causing the latex to thicken, but these starches will not absorb the type of textile dyes which are used in the present invention. Other possible dye acceptors which could conceivably be used such as the various sugars having a similar composition to dextrin, are not satisfactory dye acceptors since, due to their solubility, they leach out of the compounded latex film into the dye bath when the latex is being dyed.

In addition to the adverse effects stated above, an other difficulty associated with the use of polyvinylpyrrolidone in latex is that the modified latex does not age properly. Specifically the latex film is not light fast, which means that after exposure to an ultraviolet radiation source for a relatively short period of time, such as about 20 hours, the color of the latex fades. Normal an appreciable break in color. This fading effect indicates that the polyvinylpyrrolidone is not a commercially acceptable dye acceptor. None of the abovementioned phenomena occur when dextrin is used as the dye acceptor.

The present invention provides a novel method for dyeing any of the cured latex films disclosed herein by incorporating dextrin into the compounded latices. Dextrin possesses the right combination of properties including (1) good dye receptivity with most of the classes of dyes in textile-dyeing, (2) relatively low solubility when incorporated into the latex to resist leaching by the dye bath and (3) not affecting the chemical and mechanical stability of the latices in which it is used. The use of dextrin in the compounded latex provides an efficient method of reducing the grinning effect problem. By simply coating the back of the textile fabric substrate with a latex compound containing dextrin, the latex is dyeable with the same dyestuffs that are used to dye the textile fabric substrate during the dyeing step. Thus in the present invention the compounded latex film is dyed simultaneously with the textile fabric substrate in a single dyeing process. This method eliminates the need for pigmenting individual latex compounds for each desired fabric color. It also eliminates waste of the latex compound, unnecessary use of needed storage space, and inventory problems since only one latex compound has to be made up and coated onto the textile which can be dyed then to any desired color.

It is therefore an object of this invention to provide a dyed textile article having a cured latex coating on the back of a textile fabric substrate which is capable of being dyed to substantially the same intensity as the fibers in the textile fabric substrate.

Another object is to provide a latex compound, suitable for coating textile fabric substrates, which is colored to the same intensity as the fabric and which is fast to light and washing.

In the present invention the substrate or base layer consists of any type of woven or nonwoven textile fabric or material which can be dyed with various common textile dyes. The textile fabric used can be a woven, tufted or knitted fabric made from cotton, rayon, rayonacetate, polyester or nylon such as is used in clothing, upholstery, carpet, carpet backing, draperies, curtains, etc. Alternatively a non-woven textile material can be used such as felt, matting, or fabric which is made by the use of a resin binder to hold the fibers together or a needle punching method.

Any conventional latex of an elastomeric rubber polymer may be modified by the addition of dextrin and applied to the surface of any of the aforementioned substrates. An elastomeric polymer is a polymeric material having special properties such as being amorphous when unstretched but developing crystallinity upon stretching. It must be used above its glass transition temperature to be elastic. The elastomeric polymers used in the present invention are inherently high polymers. The useable polymers possess the characteristic of stretching and retracting rapidly and high strength and modulus while stretched, and recover on release of the stress.

Typical examples of the latices of elastomeric polymers which are used in the present invention are the following: styrene-butadiene rubber (SBR); carboxylated styrene-butadiene rubber; natural rubber; butyl rubber, which is generally a copolymer of isobutylene and 12% of a diolefin such as isoprene or butadiene; nitrile rubber, which is generally a copolymer of butadiene and acrylonitrile; a carboxylated nitrile rubber, which is generally a carboxylated copolymer of butadiene and acrylonitrile; neoprene rubber (the polymer of 2-chloro-1,3-butadiene), also known as polychloroprene; and acrylic polymers such as polymeric acrylate and methacrylate esters. Acrylic polymers are dyed by a limited number of dye classes in the unmodified form in a latex film, but the addition of dextrin affords dyeability with all of the classes of dyes mentioned in this specification. Certain additives generally are incorporated into the latices of the elastomeric polymers cited above so that the natural and synthetic rubber latices which are used in this invention have been compounded with the usual ingredients necessary for curing or vulcanization, prevention of oxidation discoloration, embrittlement and aging. In addi tion, antifoaming or defo-aming agents are used, as well as auxiliary chemicals to control wetting and penetration of latex into the textile article. These compounds can be varied selectively to obtain whatever specific properties are desired in the particular latex chosen to be used. The elastomeric polymers are present in an amount between about 25% and 98% based upon the total weight of compound solids in the film and they are preferably present in an amount between about 40% and 97% based upon the total weight of compound solids in the film.

Dextrin, which provides dyeability when incorporated into the latex in accordance with the present invention is a carbohydrate intermediate product produced from starch by hydrolysis due to the action of dilute acids, diastase, ferments or dry heat. The process of making dextrins by breaking down the long molecules of starch is called dextrinization. Dextrin is an amorphous, odorless powder which is colored white, yellow or brown. The color of the dextrin is determined by the degree of dextrinization with the white dextrin having a low degree of dextrinization and the brown colored dextrin having a high degree of dextrinization. The degree of dextrinization also determines the solubility of the dextrin in water. Thus the dextrin (white) having a low degree of dextrinization is insoluble in water whereas the dextrin (brown) having a high degree of dextrinization is soluble in water. The yellow dextrin has a solubility product value in between the solubility product of the white dextrin and the brown dextrin. Dextrin is soluble in alcohol, does not give the blue iodine reaction of starch, and it is not fermentable. Methods for making dextrin such as is used in the present invention and methods for characterizing it are found in I. A. Radley, Starch and Its Derivatives, vol. II, 3rd ed., Chapman & Hall Ltd, London (1953), pp. 107125.

In the present invention we have found that it is particularly advantageous to use between about 1 and 15 parts and preferably between about 5 and 10 parts of dextrins prepared from tapioca starch, wheat starch, potato starch, corn starch, and rice starch per 100 parts of dry weight of latex solids. Thus we use between about 1.0% and 15% of dextrin dye acceptor based upon the weight of latex solids, and preferably between about 5% and 10% of dextrin based upon the weight of latex solids. The dextrin powder which possesses a dark yellow or brown color may not be as satisfactory as the white dextrin powder since the dark color of the dextrin may affect the color of the latex into which it is incorporated, and therefore affect the true color of the dye. We prefer to use the white colored dextrin products having low dextrinization as opposed to the dark dextrin products having a high degree of dextrinization because the water solubility is less in products having a low degree of dextrinization, and therefore the leaching out of the dextrin having a loiiv degree of dextrinization from the latex into the dye bath is reduced since the dextrin with a low degree of dextrinization is relatively insoluble in the dye bath. Dextrin made from tapioca starch such as National Starch Company product number 18-53l1 provides extremely satisfactory dying results when incorporated into the latex as a dye acceptor. Other preferred dextrins are sold under the trademarks Nadex 772 and Nadex 791. An optional step which may be included in this invention if dextrin is used with a high degree of dextrinization, or if it is desired" to use a lesser amount of dextrin with a low degree of dextrinization is to add a mixture of between about 1 and parts by weight of a melamine formaldehyde resin, between about 0.25 and 2.50 parts of glyoxal (C H O also known as oxaldehyde), and between 0.1

A typical formula for the latex compound used in the present invention is set forth in Table II as follows:

TABLE II and 1.0 parts of ZnCl or MgCl to between 10 and 100 1 parts of dextrin. The exact proportions of the melamine 5 Dry Parts formaldehyde resin, glyoxal and ZnCl or MgCl added to Ingredient General Preferred the dextrin will depend on the water solubility of the par- (1) Water (2) (3) ticular dextrin used. We have found that the addition of ie{ dislpter?antls .1; .i ;i. 0. l-1.0 01 0.3 these compounds to pure dextrin greatly reduces the tend- (4) ,g,,;;, gg 33 ency of dextrin with a high degree of dextrinization to 10 t n N 100105 102-105 leach out of the latex into the dye bath. This is a congg ggi g fg s gi ffif ff H5 H0 venient way to be able to use some of the lesser preferred (7) Thickener M (4) dextnns havu 1g a hlgh degree of dextnmzanon 1n the Based upon total dry weight of latex compounded solids in the film. present invention even though they are more water soluble 3%0 gorm 35% to 70% toltallsolids. than the dextrins with a low degree of dextrinization. Also 4 3 ggfi faj g sf f y the addition of the above noted mixture to dextrin with a low degree of dextrinization results in the use of less g figfiggz gz g g g 522 :6 5: $32232 to g acc-iptor thandthat anqunthof pure fl fi g j After the latex comp und is blended it is applied to or inariy require to 0 mm t e same ept o s a e. The dextrin containing mixituge is added to the latex tgr ggy f gi i gig ggz i iifiSig 2g23222 53" latex compound an mixe t erein prior to coating e strates. As an example, the latex coating may be applied g i j g g i g igg si ggi gi g i s ig f ifigg gg to the back side of the textile fabric substrate as it passes The method of obtaining a dyeable latex treated textile 31322 15522 55 one Surface of whlch dlps Into a latex bath innacc-ordance (1th the preselntg Involves 5 25 After the application of latex to the back surface of the o owing steps in sequence. nitia y, t e compoun e latex applied to the textile fabric substratemay be com- 2x2 2 22; gifi zg g s j i i r io gfi v eii a f pounded in a single batch in a suitable mixer -by adding temperature S between about P2300 F and 350 F to a dextrin paste, which is dextrin powder mixed with a suitable amount of water to facilitalte dispersion of the g g l i s ii'fig g fi fig ggggf gi gg fgfig dextrin in the latex, to a mixture of atex and desired ad- P ditives including dispersants, vulcanizers, defoamers, ggl zi i gs gg gg g ggii g gzg figg f g 3$: :l g z fi s i the general formaldehyde resin if it is used in the compounded latex portions in icate e ow in a e I a desired additives and dextrin which has been previously any method of exhaustion y g y y mixed is added to a mixture of water filler extender dis- The dextrins used in the res nt ve to h th persant and l i z i g ludstbpnor to Thls ity of absorbing or attraciing and fix irig dyzs iifi5 3;- i gggi ggggg g g i g g sg f g ggigg g 40 cules in the latex film using all of the classes of textile facilities and therefore need only add the dextrin-oontaingi iggi lg 22 152 z figig:3 ig i gs g gfg ggfyq gi prehcOmpOund-ed latex the g 3: ester and nylon cominonly used in the trade Among er an water mixture or vice versa, to 0 mm e ethese dyestuffs are the direct dyes including direct and sired latex composition. This separate compounding develo ed, after-treated di ect; basic, ulf method requires less storagespace forthe latex compound reactivg dyes Such as cgnulose fibesr g i g w and reduces the transportation cost since water and filler ProcionS) Chrome dispersed dyes including p ia n I a 3:3 large percentage of the Welght of the latex com base diazotized; developed and acid type dyes. The follow- As noted previously the dextrin may be mixed with mg examp 1e Illustrates the mventlon' melamine-formaldehyde resin, zinc or magnesium chlo- EXAMPLE ride and glyoxal and added to the single batch Or pr A latex compound containing dextrin was applied to p f YP F fofmula a dextrin ly various textile fabric substrates indicated in Table III by COITIPOSIUOH contalnlng melamlnfi-fofmaldehyde, Zlnc passing the textile fabric substrates over a roller which chloride and glyoxal Whlch can be added to the g has one surface immersed in a latex bath, and upon rotabatch or pre-compounded latex if desired is given in tion the latex is carried along the surface of the roller Table I. until it is deposited on the back of each sample of the TABLE I Dry parts 1 Ingredient Function General Preferred (l) Dextrin acceptor Dye acceptor. 10-100 12 (3) Melamine formaldehyde resin 1.0

(4) Zinc chloride 0.25

(5) Glyoxal Cross-linking agent 0 l The dry parts are based upon 10-100 parts of dextrin. 2 To adjust to a pH of 7 to 11.

textile fabric substrate. Each of the resultant products was cured in an oven at the temperature indicated. The coated fabric was then dyed with the dyestufis shown in Table III for 1 hour at 200 F. The concentration of dye in the dye bath was varied in each case to between about .1 and 5% on weight of textile substrate and latex backing in order to obtain the same intensity of color in the latex back as in the textile substrate. Table III exemplifies the method used. The latex on each of the textile fabric substrates listed in Table III was dyed to the same color intensity as the dyed textile fabric.

TABLE III Cur- Latex, Dextrin ing parts parts temp. by I bY of Textile fabric weight Type of Dextrin (commercial weight latex,

substrate Type of latex (dry) product used) (dry) F. Dye used Rayon and SEC L 100 Nadex 791 5 260 Solantine Fast yellow acetate. R.L., (3.1. N 0. 29,025.

Do SBC 100 --.do 5 260 Setacy Blue EN 0.1

No. 61,505. Da. SEC 1 100 Nadex 772 7 260 Fastusol Orange LG GA CF 0.1. No. 40,215. Do SBC 100 -do 7 260 Acetamine Red BE 0.1.

No. 11,210. Do Natural rubber 100 Nadex 791 7 270 Paranol Fast Blue 4GL 0.1. N 0. 34,200. Do .do 100 National Starch Product 18-5311. 7 270 D Do ..do 100 N adex 772 6 280 Easignllign Fast Yellow 4 Do SBR 2 "2000 100 National Starch Product 18-5311- 10 300 Super Brilliant Blue 3GLS1. Do- Natural 100 .-d 10 325 Sirius Red F3B, 0.1. N0.

N0. 35, 780. Do SBC 100 "410 10 260 Fast Orange, UF26. Do Neoprene 842A 10 240 Cibacete Blue, Green 0,

OJ. No. 62,500. Do do 10 240 Celanthrene Brilliant :gllggsFFs, 0.1. No. Nylon and Rohm & Haas AC-33 Acrylic emulsion 10 250 Wool Red-Brown 5244.

rayon.

Do (10. 10 250 Diazo Black AW. Cotton SEC 1 10 260 Anthraquinone Vat Black BBD 5%. Do SBC 260 Naphthol A.S. 5%, 0.1.

No. 37,505. Nylon rayon SEC 1 5 270 Irgalan Yellow ZGL Extra 2%, 2GL Orange RL 3%. Cotton SEC 1 7 270 Procion Green M-2BS.

acetate.

Do SBC 7 270 Procion Brilliant Red M-SBS. Do. BBC 1 7 270 Procion Brilliant Yellow M-4GS.

1 SBO is carboxylated butadiene-styrene rubber. 1 SEE is styrene-butadiene rubber.

3 Neoprene 842A-A polychloroprene latex of approximately solids and a particle size 0150-190 millimicrons.

4 Acrylic emulsion-A polyaerylic and polymer latex of 46% solids.

We have determined that the above mentioned dyes can be mixed in one dye bath if a cross dyeing effect is desired. In this case the total concentration of the dyes exceeded 5% but the individual concentration of each dye used in the mixture of dyes did not exceed 5% Having thus described our invention what We d sire to claim and protect by Letters Patent is:

1. In a dyed rubber coated textile fabric comprising, (A) a textile fabric substrate, and (B) an elastomeric polymer film coating thereon, wherein both fabric and elastomeric polymer film coating thereon are dyed to substantially the same shade in a single dyebath with textile dyes, the improvement wherein said film comprises (a) between about 25% and 98% of a cured elastomeric polymer based upon the total Weight of compound solids in the film, in admixture with as a dye acceptor (b) between about one part and 15 parts of dextrin based upon 100 parts of dry rubber of said elastorubber, nitrile rubber, carboxylated nitrile rubber, neoprene rubber, and acrylic polymer.

3. The dyed latex coated textile fabric as defined in claim 2 in which the textile dye used to dye said article is selected from the group consisting of direct, basic, sulfur, gzoic, vat, reactive, dispersed, developed and acid type yes.

4. The latex coated textile fabric as defined in claim 1 in which the compounded latex film contains a mixture having between about 1 and 10 parts of dextrin, between about 0.25 and 2.50 parts of glyoxal per 10 to parts of dextrin and between about 0.1 and 1.0 parts of zinc chloride per 10 to 100 parts of dextrin.

S. In a method of preparing a dyed rubber coated textile fabric comprising applying a compounded latex containing between about 25% and 98% of an elastomeric polymer based upon the total weight of compound solids to a textile fabric substrate, drying and vulcanizing said latex thereon to form an elastomeric film, and subjecting said latex coated textile fabric to a subsequent dyeing treatment with a textile dye, the improvement comprising incorporating into said compounded latex as a dye acceptor between about 1 part and 15 parts of dextrin based upon 100 parts of elastomer polymer whereby said elastomeric film and said textile fabric substrate are dyed to substantially the same shade in a single dyebath.

6. A method of preparing a latex coated textile fabric as defined in claim 5 in which the elastomeric polymer is selected from the group consisting of styrene-butadiene rubber, carboxylated styrene-butadiene rubber, natural rubber, butyl rubber, nitrile rubber, carboxylated nitrile rubber, neoprene rubber, and acrylic polymer.

7. A method of preparing a latex coated textile fabric as defined in claim 6 in which the textile dye is selected from the group consisting of direct, basic, sulfur, azoic, vat, reactive, dispersed, developed and acid type dyes.

10 References Cited UNITED STATES PATENTS 6/1964 Swiggett 818 4/ 1939 OBrien 891 FOREIGN PATENTS 10/ 1938 Great Britain.

OTHER REFERENCES F. Marchionna: Latex and Rubber Derivatives, vol. 11,

US. Cl. X.R. 

